Bot. Gaz. 48: 147. 1909.
Herbs, perennial, 0.8–2.5 dm; from a woody caudex; with a taproot. Stems few-to-many, ± curved at base, ascending or erect distally, unbranched, hairs moderately dense, spreading, medium length and long, soft, mixed with shorter stipitate-glandular ones. Leaves green, sometimes purple-tinged, lanceolate, broadly lanceolate, or narrowly ovate, 1–4.3 cm, not fleshy, margins plane, sometimes ± wavy, ± involute, 0–3-lobed, apex acute to acuminate; lobes ascending, often narrowly oblanceolate, apex acute to acuminate. Inflorescences 3–8.5 × 1–4 cm; bracts greenish or bright to sometimes dull red, sometimes scarlet, orange, or pale-pink throughout, or proximally greenish, distally as above, ovate to elliptic, (0–) 3-lobed; lobes ascending, lanceolate to narrowly triangular, short, arising above mid length, apex acute to obtuse or acuminate. Calyces brightly, conspicuously colored for at least distal 2/3, often throughout, providing much of inflorescence coloration, proximally pale whitish to pale-pink, distally colored as in distal portion of bracts, sometimes colored throughout as in distal portion of bracts, 15–30 mm; abaxial and adaxial clefts 7–14 mm, 33–50% of calyx length, deeper than laterals, lateral 1–5 mm, 5–15% of calyx length; lobes narrowly to broadly triangular, apex rounded to acute. Corollas straight or slightly curved, 20–40 mm; tube 27 mm; abaxial lip often visible in abaxial cleft, sometimes exserted, beak usually exserted from calyx; beak adaxially green to yellow, 8–14 mm; abaxial lip red, black, green, white, or green-and-white, ± prominent, slightly rounded, 1.5–5 mm, ca. 33% as long as beak; teeth ascending, green, bright red, pink, white, or yellow, 0.5–3 mm.
Phenology: Flowering Jul–Aug(–Sep).
Habitat: Moist or dry rocky slopes and flats, ridges, talus, dwarf willow mats, subalpine to alpine, rarely along stream channels at lower elevations, over sedimentary rocks, often limy.
Elevation: 2000–2900 m.
Castilleja fraterna is endemic to one ridge system in the Wallowa Mountains of northeastern Oregon. A parallel ridge system in the range has a second Wallowa Mountains endemic, C. rubida. Castilleja fraterna is colored similarly to C. miniata, but the petaloid teeth of the abaxial corolla lip are more like C. chrysantha. It is possible that C. fraterna was derived through hybridization, though its chromosome number is unknown. It resembles the newly described C. kerryana in Montana.
"arising" is not a number.